Variability in Perimetry Study (VIPII)

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Number of Subjects Progressing in Each Group Using Pointwise Linear Regression [ Time Frame: 4 years ]

Perimetric method that most efficiently detects visual field change. secondary outcome: number of subjects progressing in each group using pointwise linear regression Linear regression was used to determine visual field worsening (progression) at each of 52 test locations. We required 3 or more worsening test locations at a p = 0.05 significance level for their to be significant progression.

Improved Assessment of Visual Field Change is a trial aimed at investigating mechanisms of visual field testing variability. The investigators have found using larger stimulus size substantially lowers short-term variability. In this study, the investigators will determine if larger stimuli detect visual field change at an earlier time. The investigators are also developing a statistical model that accounts for correlations of neighboring test locations.

Detailed Description

Disease of the optic nerve, including glaucoma, is the leading cause of blindness in the United States. Treatment decisions for optic nerve diseases are based largely on the changes in visual function that occur mostly as a consequence of disease progression. Unfortunately, the decision as to whether change of visual function has occurred is often difficult because of the high retest variability of conventional visual field testing (perimetry). This variability is so high that with moderate visual loss, a minimum of six tests are often needed in patients with optic nerve damage to reliably distinguish visual field deterioration from random variation. The preliminary data show that a substantial portion of the variability of perimetry lies in the type of stimulus used and the testing strategy applied.

OBJECTIVES: The investigators propose to test the hypothesis that a large portion of total perimetric variability in patients with visual loss is due to a poor signal-to-noise ratio associated with using a small fixed-size stimulus.

RESEARCH PLAN AND METHODS: To test this hypothesis, the investigators are examining patients with optic nerve diseases with conventional automated perimetry (size III) and tests having large-sized and scaled stimuli (size V, size VI (custom perimeter) and luminance size threshold perimetry - a test where threshold is found by changing stimulus size rather than stimulus intensity). Over four years the investigators will test 100 patients with and glaucoma and 60 normals each eight times. In addition, the investigators are retesting 50 subjects once a week for 5 weeks. The investigators are also studying the associated structural-functional correlations using OCT and developing a statistical model that accounts for correlations of neighboring test locations.

Perimetric variability and the reliable identification of visual field change is the single most difficult problem in visual testing today. The investigators anticipate identifying a method that allows efficient and accurate determination of visual field change. Identification of a superior method would (1) reduce the number of examinations needed, thereby reducing the costs of medical care; (2) minimize misdiagnosis, unnecessary testing and even unnecessary surgery that results from mistakenly interpreting fluctuation of the visual field as progression or improvement; (3) allow earlier disease intervention and (4) reduce the costs of clinical trials.

Study Type

Observational

Study Design

Observational Model: Case-ControlTime Perspective: Prospective

Target Follow-Up Duration

Not Provided

Biospecimen

Not Provided

Sampling Method

Probability Sample

Study Population

glaucoma patient with 0 to -25 dB mean deviation and normal subjects

Condition

Glaucoma

Intervention

Procedure: Comparison of four visual field testing strategies

We compared the ability of four perimetric strategies to detect visual field change in the glaucoma arm.

Study Groups/Cohorts

Group 1

glaucoma

Intervention: Procedure: Comparison of four visual field testing strategies

Group 2

normal

Intervention: Procedure: Comparison of four visual field testing strategies